The following is a description of the most pertinent prior art of which applicants are aware:
The basic patent describing a scanning tunneling microscope (STM) is U.S. Pat. No. 4,343,993. An STM is an instrument capable of sensing atomic scale variations in the height of a surface by maintaining tunneling current constant as the surface is being scanned. This STM technology has been extended to various applications employing a tunneling tip in close proximity to a surface for producing surface modifications.
U.S. Pat. No. 4,829,507 discloses a method of writing indicia on an adsorbent carrier surface of a recording medium by using a tunneling tip and adding individual adsorbate atomic particles to the surface from a source other than the tip.
An article in the Feb. 1, 1988 issue of Journal of Applied Physics at pp. 717-721, discloses the use of a tunneling tip of platinum-iridium material which is moved to within current tunneling range of a gold surface which is coated with a fluorocarbon grease. Applying a voltage of roughly 1 volt between the tip and surface for roughly 1 second results in a balling up of the gold under the tip, leaving a small well-defined bump. Gold is preferred under ambient conditions because it does not oxidize, and the grease provides an additional protective coating. Platinum-iridium tips are commercially available and rather inert. This process has the disadvantage of being slow since voltage pulses of approximately 1 second are required. Also, the bump is not formed from atomic particles provided by the tunneling tip as the source.
U.S. Pat. No. 4,896,044 discloses use of a tunneling tip which is moved within current tunneling range over a gold surface to remove gold atoms from the surface and thereby pit the surface at selected locations for writing indicia thereat. Again, there is no teaching or suggestion of depositing atomic particles removed from a tunneling tip.
The unexamined Japanese Patent Application published Nov. 1, 1988 as 63-265101 in the Patent Abstracts of Japan discloses a way to reform a STM tip by applying a high voltage to it, causing atoms to be evaporated in the high electric field. There is no teaching or even suggestion of collecting the emitted atoms for any purpose, nor any reason to believe that such evaporation might be localized and continuous as part of a writing process.
There is a need for a simplified, efficient, reliable method of writing rapidly on a surface by depositing atomic scale structures on the surface with a scanning or tunneling tip in a manner which can be effected at ambient temperature and pressure.